Device for heating and fixing toner images upon a recording medium

ABSTRACT

A non-adhesive endless belt is used for heating and fixing toner images upon a recording medium by mounting the belt on a roller having means for heating it and on a driving roller spaced apart from the heated roller means. The recording medium is passed closely adjacent to or with its toner-carrying surface in contact with the surface of the heated belt to fuse the toner in the form of the image on the recording medium. Cleaning means and a preheated pressure roller are also provided to improve the quality of the fused toner image.

United States Patent 1191 Ohta et al. 1 Feb. 13, 1973 [541 DEVICE FOR HEATING AND FIXING 2,556,008 6/1951 Spalding ..219 19 TONER IMAGES UPON A RECORDING 3,374,769 3/1968 Carlson o ..l18/64l 3,132,047 5/1964 Van Dorn ..118/637 MEDIUM 3,377,598 4/1968 Borman ..118/101 [75] Invento s: Wasaburo O ta. Y ham Ka u- 2,684,047 7 1954 Walker ..1 18/101 hiko Kasuya, Kawasaki, both of Japan Primary Examiner-Mervin Stein [73] Assignee: Ricoh Co., Ltd., Tokyo, Japan Amsmm Mnstem Att0rneyHenry T. Burke, Robert Scobey, Robert S. Flledi 19,70 Dunham, P. E. Henninger, Lester W. Clark, Gerald [211 App]. 78,486 W. Griffin, Thomas F. Moran, R. Bradlee Boal and Christopher C. Dunham [30] Foreign Application Priority Data 57 ABSTRACT Oct. 9, 1969 Japan ..44/8137l A nomadhesive end|ess belt is used f heating and fixing toner images upon a recording medium by [52] US. Cl. ..Il8/l0l, 118/60, 1 18/202, mounting the be on a roller having means for heating I 18/641 it and on a driving roller spaced apart from the heated [51] Int. Cl ..B05C 11/02 roner means. The recording medium is passed closely [58] Field of Search ..118/101, 202, 257, 641, 637,

[56] References Cited UNITED STATES PATENTS 3,605,690 9/1971 Staller ..1 18/637 3,161,529 12/1964 Curme ..117/17.5

adjacent to or with its toner-carrying surface in contact with the surface of the heated belt to fuse the toner in the form of the image on the recording medium. Cleaning means and a preheated pressure roller are also provided to improve the quality of the fused toner image.

8 Claims, 6 Drawing Figures PAIENTEDFEBICB 1975 3.716.018

INVENTORS WAS/IBUPO OHM Y KAZZ/H/KO msum BACKGROUND OF THE INVENTION :r The present invention relates to a device'for heating and fixing toner images upon a recording medium in an electrophotographic process using dry methods or. a thermographic process.

Heat fixing is generally employed for fixing a visible image, for example, formed by toner containing easily fusible resin in an electrophotographic process by dry method. A heat source is employed such as an infrared ray lamp, a halogen lamp or a nichrome wire so that the visible image may be heated to a temperature between 100C and 1s0"c so as to be fused. However, this method has disadvantages in that the time required for raising the temperature of the visible image to a fixing temperature is quite long;'the thermal efficiency is low;

and other parts of the apparatus become heated. To overcome these problems, there have been proposed various methods, but none has been particularly successful in reducing the rise time for reaching the fixing temperature and accomplishing the perfect fixing at high speed. I

SUMMARY OF THE INVENTION One of the objects of the present inventionis to overcome the problems of the prior art device described above. p

Another object of the present invention is to provide an arrangement in which a recording medium is not brought into direct contact with a heating means and is prevented from being over-heated.

Another object of the present invention is to provide an arrangement for preventing the toner from being adhered to an endless belt for heating the toner.

Another object of the present-invention is to provide an arrangement for facilitating the easy removal of the toner adhered to the endless belt.

Another object of the present invention is to prevent overheating ofthe endless belt.

2 DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view in elevation a fundamental heating and fusing device in accordance with the present invention;

FIGS. 2 and 3 are sectional views as in FIG. 1 illustrating additional features thereof;

FIG. 4-A and FIG. 4B are side views illustrating the copies used in thermographic process; and

FIG. 5 is a sectional view in elevation of a device in accordance with the present invention for accomplishing the thermographic development of the copies shown in FIGS. 4-A and 4-B.

. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates the fundamental arrangement of the present invention, in which a visible image 2 is formed by a developing agent (toner) containing fusible resins upon a recording medium 1 advanced in the a halogen lamp, a nichrome wire, etc. Alternatively,- the According to oneaspectof the present invention, a

non-adhesive endless belt is used for heating thetoner upon a recording medium. The endless belt rides about a heating roller incorporating therein a heater and a drive roller spaced apart from the heating roller so that the endless belt may be suitably cooledby the time it returns to the heatingvroller after it haslfused thetoner on the recording mediurnrThat is, the overheating of the endless belt maybeprevented. The endless belt for heating the toner may be brought into direct contact with the recording medium or may be spaced apart therefrom by a suitable distance. Preferably a rotary cleaning brush may be. positionedin contact with the endless belt for removal of the toner and other contaminants which cling to the endless belt. This arranger'nentis especially advantageous when the endless belt is in direct contact with'the recording medium.

A device in accordance with the present invention maybe used for heatinga heat-sensitive substance such as, for example, aheat-sensitive paper or a'stencil.

The present invention will become more apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.

roller 4 may serve as a heater. The toner is heated and fixed to the recording medium 1, so that the permanent image 8 may be formed. The endless belt 5 which wraps in it the hollow roller 4 and a spaced drive roller 6 is advanced at the same speed as that of the recording medium I in the direction b. A pressure roller 7 rotating in the direction indicated by the arrow c has its peripheral surface covered with an elastic member such as thermostable rubber capable of withstanding a temperature of 200 C and serves to press the toner image 2 against the endless belt 5 and to prevent the toner'image from being distorted. The fixing speed of the visible image may be improved when the pressure roller 7 is preheated to a temperature from 60 to C.

When the surface of the endless belt 5 is moved away from the heating roller 4, its temperature is lowered by cooling so that any toner attached thereto is sufficiently cooled to be easily removed from the endless roller 5. Furthermore, temperature control of the heating roller may be easily achieved.

In FIGS. 2 to 5, members which function as those in the embodiment illustrated in FIG. 1 are indicated by the same reference numerals. Therefore, the explanation of these members will not be made. In the. embodiment illustrated in FIG. 2, a cleaningbrush 9 rotates in the same direction with that of the roller 6 so as to clean the endless belt 5. Therefore, the endless belt 5 free from the toner may be always brought into contact with the heating roller 4.

The cleaning brush 9 is spaced apart from the heating roller 4 so that the aging of the cleaning brush 9 may be prevented. That is, the service life may be extended. As the endless belt 5 moves away from the heating roller 4, the toner attached thereupon is cooled, so that the removal of the toner upon the endless belt 5 may be further improved.

The embodiment illustrated in FIG. 3 is provided with an application roller 10 for applying silicon oil or the like over the endless belt Sin order to form a nonadhesive layer thereupon The application roller is coated with a permeable substance such as cloth 9' for holding silicon oil therein. The'application roller 10 rotates about a shaft 11 and makes contact with the endless belt 5 so that the non-adhesive layer may be formed upon the endless belt 5. Therefore non-adhesiveness of the endless belt surface 5 may be further improved.

FIG. 4-A and FIG. 4-B are side views of a heat-sensitive substance (thermographic copy) illustrating its thermographic process. The copy is, for example, a stencil. In FIG. 4-A, reference numeral 12 designates a heat-sensitive copy made of a porous paper or plastic sheet with waxy backing; and 13, an original to be reproduced in registration with the copy 12. lnfrared rays are irradiated from the back of the copy 12 so that the image (or printing) portion upon the original 13 (generally a black-colored portion) absorbs much infrared rays. The heat rays irradiated from the image or printing portion 13a upon the original 12 which is heated to a high temperature by the infrared rays 15 heats a portion on the copy 12 corresponding to the image or printing portion 13a of the original 13. In consequence, wax is melted so that the porous paper or plastic sheet 12a is exposed. The infrared rays 14 incident upon a non-image portion ornon-printing portion upon the original 13 are reflected and dissipated as shown by 16. Consequently, the temperature of the non-printing portion is not raised, so that a portion on the copy 12 corresponding to this non-printing portion will not melt..The reproduced copy 12 may be used as stencil in mimeographing.

The embodiment illustrated in FIG. 5 is for accomplishing the thermographic process whose principle has been explained with reference toFlG. 4-A and FIG. 4-B, by a heater in accordance with the present invention. The original 13 is placed over the copy 12 as shown and they are passed through the nip between the heating roller 4 and the pressure roller 7 in the direction indicated by the arrow 0. Thus, the thermographic process may be accomplished. The processing speed may be improved when the pressure roller 7 is pre-heated. The endless belt 5 serves to easily control the temperaturein the thermographic process.

What is claimed is:

1. A device for heating and fixing a toner image upon a toner-carrying recording medium being transported thereby comprising:

a. a heating roller disposed adjacent the path of travel of said recording medium;

b. an endless belt made of a thermostable substance and mounted for travel around said heating roller so as to transfer heat from said roller to the tonercarrying surface of said recording medium to fuse the toner thereon;

c. means for driving said endless belt in the same direction as that of said recording medium; and

d. a preheated pressure roller positioned opposite said heating roller and cooperating with said heating roller to pass said recording medium under pressure between them.

2. The device defined in claim 1 wherein said endless belt is made of a non-adhesive material.

3. The device defined in claim 1 wherein said heating roller is spaced agart from said belt-driving means.

4. The device efined in claim 1,1ncludmg means for cleaning the surface of said endless belt.

5. The device defined in claim 4 wherein said cleaning means is a rotating brush.

6. The device defined in claim 1 wherein an application means is provided for applying a non-adhesive coating upon the surface of said non-adhesive endless belt.

7. The device defined in claim 6 wherein said application means is a application roller coated with a permeable substance.

8. A device as in claim 1, wherein the pressure roller has a thermostable surface. 

1. A device for heating and fixing a toner image upon a toner-carrying recording medium being transported thereby comprising: a. a heating roller disposed adjacent the path of travel of said recording medium; b. an endless belt made of a thermostable substance and mounted for travel around said heating roller so as to transfer heat from said roller to the toner-carrying surface of said recording medium to fuse the toner thereon; c. means for driving said endless belt in the same direction as that of said recording medium; and d. a preheated pressure roller positioned opposite said heating roller and cooperating with said heating roller to pass said recording medium under pressure between them.
 1. A device for heating and fixing a toner image upon a tonercarrying recording medium being transported thereby comprising: a. a heating roller disposed adjacent the path of travel of said recording medium; b. an endless belt made of a thermostable substance and mounted for travel around said heating roller so as to transfer heat from said roller to the toner-carrying surface of said recording medium to fuse the toner thereon; c. means for driving said endless belt in the same direction as that of said recording medium; and d. a preheated pressure roller positioned opposite said heating roller and cooperating with said heating roller to pass said recording medium under pressure between them.
 2. The device defined in claim 1 wherein said endless belt is made of a non-adhesive material.
 3. The device defined in claim 1 wherein said heating roller is spaced apart from said belt-driving means.
 4. The device defined in claim 1, including means for cleaning the surface of said endless belt.
 5. The device defined in claim 4 wherein said cleaning means is a rotating brush.
 6. The device defined in claim 1 wherein an application means is provided for applying a non-adhesive coating upon the surface of said non-adhesive endless belt.
 7. The device defined in claim 6 wherein said application means is a application roller coated with a permeable substance. 